I am having dependency troubles. I have two classes: Graphic
and Image
. Each one has its own .cpp and .h files. I am declaring them as the following:
我有依赖性麻烦。我有两个类:图形和图像。每个人都有自己的.cpp和.h文件。我将它们声明如下:
Graphic.h
:
#include "Image.h"
class Image;
class Graphic {
...
};
Image.h
:
#include "Graphic.h"
class Graphic;
class Image : public Graphic {
...
};
When I try to compile, I get the following error:
当我尝试编译时,我收到以下错误:
Image.h:12: error: expected class-name before ‘{’ token
If I remove the forward declaration of Graphic
from Image.h
I get the following error:
如果我从Image.h中删除Graphic的前向声明,我会收到以下错误:
Image.h:13: error: invalid use of incomplete type ‘struct Graphic’ Image.h:10: error: forward declaration of ‘struct Graphic’
5 个解决方案
#1
10
This worked for me:
这对我有用:
Image.h:
#ifndef IMAGE_H
#define IMAGE_H
#include "Graphic.h"
class Image : public Graphic {
};
#endif
Graphic.h:
#ifndef GRAPHIC_H
#define GRAPHIC_H
#include "Image.h"
class Graphic {
};
#endif
The following code compiles with no error:
以下代码编译时没有错误:
#include "Graphic.h"
int main()
{
return 0;
}
#2
5
You don't need to include Image.h or forward declare Image in Graphic.h - that's a circular dependency. If Graphic.h depends on anything in Image.h you need to split that out into a third header. (If Graphic has an Image member, that just isn't going to work.)
您不需要在Graphic.h中包含Image.h或forward declare Image - 这是一个循环依赖。如果Graphic.h依赖于Image.h中的任何内容,则需要将其拆分为第三个标头。 (如果Graphic有一个Image成员,那就不行了。)
#3
4
Graphic.h doesn't need to include image.h, and it doesn't need to forward declare the Image class. Also, Image.h doesn't need to forward declare the Graphic class since you #include the file that defines that class (as you must).
Graphic.h不需要包含image.h,也不需要转发声明Image类。此外,Image.h不需要转发声明Graphic类,因为#include定义该类的文件(如您所愿)。
Graphic.h:
class Graphic {
...
};
Image.h
:
#include "Graphic.h"
class Image : public Graphic {
...
};
#4
1
Since Image extends Graphic, remove the inclusion of Image in your Graphic.h file.
由于Image扩展了Graphic,因此在Graphic.h文件中删除Image的包含。
Graphic.h
class Graphic {
...
};
#5
0
First remove this, you must always have the complete class definition available in order to inherit from a class:
首先删除它,您必须始终拥有完整的类定义才能从类继承:
class Graphic;
Second, remove all references to Image from Graphic.h. The parent will usually not need to know of its childs.
其次,从Graphic.h中删除对Image的所有引用。父母通常不需要知道其孩子。
#1
10
This worked for me:
这对我有用:
Image.h:
#ifndef IMAGE_H
#define IMAGE_H
#include "Graphic.h"
class Image : public Graphic {
};
#endif
Graphic.h:
#ifndef GRAPHIC_H
#define GRAPHIC_H
#include "Image.h"
class Graphic {
};
#endif
The following code compiles with no error:
以下代码编译时没有错误:
#include "Graphic.h"
int main()
{
return 0;
}
#2
5
You don't need to include Image.h or forward declare Image in Graphic.h - that's a circular dependency. If Graphic.h depends on anything in Image.h you need to split that out into a third header. (If Graphic has an Image member, that just isn't going to work.)
您不需要在Graphic.h中包含Image.h或forward declare Image - 这是一个循环依赖。如果Graphic.h依赖于Image.h中的任何内容,则需要将其拆分为第三个标头。 (如果Graphic有一个Image成员,那就不行了。)
#3
4
Graphic.h doesn't need to include image.h, and it doesn't need to forward declare the Image class. Also, Image.h doesn't need to forward declare the Graphic class since you #include the file that defines that class (as you must).
Graphic.h不需要包含image.h,也不需要转发声明Image类。此外,Image.h不需要转发声明Graphic类,因为#include定义该类的文件(如您所愿)。
Graphic.h:
class Graphic {
...
};
Image.h
:
#include "Graphic.h"
class Image : public Graphic {
...
};
#4
1
Since Image extends Graphic, remove the inclusion of Image in your Graphic.h file.
由于Image扩展了Graphic,因此在Graphic.h文件中删除Image的包含。
Graphic.h
class Graphic {
...
};
#5
0
First remove this, you must always have the complete class definition available in order to inherit from a class:
首先删除它,您必须始终拥有完整的类定义才能从类继承:
class Graphic;
Second, remove all references to Image from Graphic.h. The parent will usually not need to know of its childs.
其次,从Graphic.h中删除对Image的所有引用。父母通常不需要知道其孩子。